This excellent short story by Stephen Crane bears many different hallmarks of Realist literature of the time. Let us just briefly remind ourselves about some of the characteristics of Realism. Realistic texts reject the idealised hero of Romantic literature, they give a detailed presentation of ordinary characters and grimly realistic events, they focus on characters from the lower classes and focus on the brutal realities of real-life situations.
We can automatically see a number of these elements in "A Mystery of Heroism." Firstly, it is told from a common point of view, focussing on Private Fred Collins and his exploits. Secondly, it is set during a heated battle during the Civil War, giving us grim descriptions of the realities of such a situation for soldiers such as Fred Collins. Note the following description:
One of a "swing" team was suddenly smitten quivering ot the ground and his maddened brethren dragged his torn body in their struggle to escape from this turmoil and danger. A young soldier astride one of the leaders swore and fumed in his saddle and furiously jerked at the bridle. An officer screamed out an order so violently that his voice broke and ended the sentence in a falsetto shriek.
Note the intense realism of this description. Men are shown to die in brutal, violent and instantaneous ways. Soldiers and officers are shown to be vulnerable to the intense pressure they are under, swearing and shrieking. There is no sense in which characters are presented as idealised heroes.
Lastly, through this text Crane explores the concept of heroism and war, with grim irony pointing out the futility of both of these concepts. After all of his efforts and bravery to get the bucket of water for the men, the bucket is accidentally knocked over and the precious water, which Fred Collins had risked so much for, ends up on the dirt. Is this really what we risk our lives for in war, Crane seems to ask?